Annotate all public methods.

src/libraries/Common/src/Interop/Windows/WinSock/Interop.getsockopt.cs

@@ -22,7 +22,7 @@ internal static extern SocketError getsockopt(
             [In] SafeSocketHandle socketHandle,
             [In] SocketOptionLevel optionLevel,
             [In] SocketOptionName optionName,
-            [Out] byte[]? optionValue,
+            [Out] byte[] optionValue,
             [In, Out] ref int optionLength);
 
         [DllImport(Interop.Libraries.Ws2_32, SetLastError = true)]

src/libraries/System.Net.Sockets/src/System/Net/Sockets/IOControlKeepAlive.Windows.cs

@@ -23,7 +23,7 @@ internal sealed class IOControlKeepAlive
 
         public static bool IsNeeded => !s_supportsKeepAliveViaSocketOption;
 
-        public static SocketError Get(SafeSocketHandle handle, SocketOptionName optionName, byte[]? optionValueSeconds, ref int optionLength)
+        public static SocketError Get(SafeSocketHandle handle, SocketOptionName optionName, byte[] optionValueSeconds, ref int optionLength)
         {
             if (optionValueSeconds == null ||
                 !BitConverter.TryWriteBytes(optionValueSeconds.AsSpan(), Get(handle, optionName)))

src/libraries/System.Net.Sockets/src/System/Net/Sockets/Socket.Unix.cs

@@ -138,7 +138,7 @@ private static void CheckTransmitFileOptions(TransmitFileOptions flags)
             }
         }
 
-        private void SendFileInternal(string fileName, byte[]? preBuffer, byte[]? postBuffer, TransmitFileOptions flags)
+        private void SendFileInternal(string? fileName, byte[]? preBuffer, byte[]? postBuffer, TransmitFileOptions flags)
         {
             CheckTransmitFileOptions(flags);
 
@@ -219,7 +219,7 @@ private async Task SendFileInternalAsync(FileStream? fileStream, byte[]? preBuff
             }
         }
 
-        private IAsyncResult BeginSendFileInternal(string fileName, byte[]? preBuffer, byte[]? postBuffer, TransmitFileOptions flags, AsyncCallback? callback, object? state)
+        private IAsyncResult BeginSendFileInternal(string? fileName, byte[]? preBuffer, byte[]? postBuffer, TransmitFileOptions flags, AsyncCallback? callback, object? state)
         {
             CheckTransmitFileOptions(flags);
 

src/libraries/System.Net.Sockets/src/System/Net/Sockets/Socket.Windows.cs

@@ -333,7 +333,7 @@ private Socket GetOrCreateAcceptSocket(Socket? acceptSocket, bool checkDisconnec
             return acceptSocket;
         }
 
-        private void SendFileInternal(string fileName, byte[]? preBuffer, byte[]? postBuffer, TransmitFileOptions flags)
+        private void SendFileInternal(string? fileName, byte[]? preBuffer, byte[]? postBuffer, TransmitFileOptions flags)
         {
             // Open the file, if any
             FileStream? fileStream = OpenFile(fileName);
@@ -363,7 +363,7 @@ private void SendFileInternal(string fileName, byte[]? preBuffer, byte[]? postBu
             }
         }
 
-        private IAsyncResult BeginSendFileInternal(string fileName, byte[]? preBuffer, byte[]? postBuffer, TransmitFileOptions flags, AsyncCallback? callback, object? state)
+        private IAsyncResult BeginSendFileInternal(string? fileName, byte[]? preBuffer, byte[]? postBuffer, TransmitFileOptions flags, AsyncCallback? callback, object? state)
         {
             FileStream? fileStream = OpenFile(fileName);
 

src/libraries/System.Net.Sockets/src/System/Net/Sockets/Socket.cs

@@ -1217,12 +1217,12 @@ public int Send(ReadOnlySpan<byte> buffer, SocketFlags socketFlags, out SocketEr
             return bytesTransferred;
         }
 
-        public void SendFile(string fileName)
+        public void SendFile(string? fileName)
         {
             SendFile(fileName, null, null, TransmitFileOptions.UseDefaultWorkerThread);
         }
 
-        public void SendFile(string fileName, byte[]? preBuffer, byte[]? postBuffer, TransmitFileOptions flags)
+        public void SendFile(string? fileName, byte[]? preBuffer, byte[]? postBuffer, TransmitFileOptions flags)
         {
             if (NetEventSource.IsEnabled) NetEventSource.Enter(this);
 
@@ -1706,7 +1706,7 @@ public int ReceiveFrom(byte[] buffer, ref EndPoint remoteEP)
             return ReceiveFrom(buffer, 0, buffer != null ? buffer.Length : 0, SocketFlags.None, ref remoteEP);
         }
 
-        public int IOControl(int ioControlCode, byte[] optionInValue, byte[] optionOutValue)
+        public int IOControl(int ioControlCode, byte[]? optionInValue, byte[]? optionOutValue)
         {
             ThrowIfDisposed();
 
@@ -1729,7 +1729,7 @@ public int IOControl(int ioControlCode, byte[] optionInValue, byte[] optionOutVa
             return realOptionLength;
         }
 
-        public int IOControl(IOControlCode ioControlCode, byte[] optionInValue, byte[] optionOutValue)
+        public int IOControl(IOControlCode ioControlCode, byte[]? optionInValue, byte[]? optionOutValue)
         {
             return IOControl(unchecked((int)ioControlCode), optionInValue, optionOutValue);
         }
@@ -1856,7 +1856,7 @@ public void SetSocketOption(SocketOptionLevel optionLevel, SocketOptionName opti
             return optionValue;
         }
 
-        public void GetSocketOption(SocketOptionLevel optionLevel, SocketOptionName optionName, byte[]? optionValue)
+        public void GetSocketOption(SocketOptionLevel optionLevel, SocketOptionName optionName, byte[] optionValue)
         {
             ThrowIfDisposed();
 
@@ -1867,7 +1867,7 @@ public void GetSocketOption(SocketOptionLevel optionLevel, SocketOptionName opti
                 _handle,
                 optionLevel,
                 optionName,
-                optionValue,
+                optionValue!,
                 ref optionLength);
 
             if (NetEventSource.IsEnabled) NetEventSource.Info(this, $"Interop.Winsock.getsockopt returns errorCode:{errorCode}");
@@ -2459,7 +2459,7 @@ private SocketError DoBeginSend(byte[] buffer, int offset, int size, SocketFlags
             return errorCode;
         }
 
-        public IAsyncResult BeginSend(IList<ArraySegment<byte>> buffers, SocketFlags socketFlags, AsyncCallback callback, object state)
+        public IAsyncResult BeginSend(IList<ArraySegment<byte>> buffers, SocketFlags socketFlags, AsyncCallback? callback, object? state)
         {
             SocketError errorCode;
             IAsyncResult? result = BeginSend(buffers, socketFlags, out errorCode, callback, state);
@@ -2470,7 +2470,7 @@ public IAsyncResult BeginSend(IList<ArraySegment<byte>> buffers, SocketFlags soc
             return result!;
         }
 
-        public IAsyncResult? BeginSend(IList<ArraySegment<byte>> buffers, SocketFlags socketFlags, out SocketError errorCode, AsyncCallback callback, object state)
+        public IAsyncResult? BeginSend(IList<ArraySegment<byte>> buffers, SocketFlags socketFlags, out SocketError errorCode, AsyncCallback? callback, object? state)
         {
             if (NetEventSource.IsEnabled) NetEventSource.Enter(this);
             ThrowIfDisposed();
@@ -2592,12 +2592,12 @@ public int EndSend(IAsyncResult asyncResult, out SocketError errorCode)
             return bytesTransferred;
         }
 
-        public IAsyncResult BeginSendFile(string fileName, AsyncCallback callback, object state)
+        public IAsyncResult BeginSendFile(string? fileName, AsyncCallback? callback, object? state)
         {
             return BeginSendFile(fileName, null, null, TransmitFileOptions.UseDefaultWorkerThread, callback, state);
         }
 
-        public IAsyncResult BeginSendFile(string fileName, byte[]? preBuffer, byte[]? postBuffer, TransmitFileOptions flags, AsyncCallback? callback, object? state)
+        public IAsyncResult BeginSendFile(string? fileName, byte[]? preBuffer, byte[]? postBuffer, TransmitFileOptions flags, AsyncCallback? callback, object? state)
         {
             if (NetEventSource.IsEnabled) NetEventSource.Enter(this);
 
@@ -3040,7 +3040,7 @@ public int EndReceive(IAsyncResult asyncResult, out SocketError errorCode)
             return bytesTransferred;
         }
 
-        public IAsyncResult BeginReceiveMessageFrom(byte[] buffer, int offset, int size, SocketFlags socketFlags, ref EndPoint remoteEP, AsyncCallback callback, object state)
+        public IAsyncResult BeginReceiveMessageFrom(byte[] buffer, int offset, int size, SocketFlags socketFlags, ref EndPoint remoteEP, AsyncCallback? callback, object? state)
         {
             if (NetEventSource.IsEnabled)
             {
@@ -3445,7 +3445,7 @@ public int EndReceiveFrom(IAsyncResult asyncResult, ref EndPoint endPoint)
         // Return Value:
         //
         //    IAsyncResult - Async result used to retrieve resultant new socket
-        public IAsyncResult BeginAccept(AsyncCallback callback, object state)
+        public IAsyncResult BeginAccept(AsyncCallback? callback, object? state)
         {
             if (!_isDisconnected)
             {
@@ -3459,13 +3459,13 @@ public IAsyncResult BeginAccept(AsyncCallback callback, object state)
             return null; // unreachable
         }
 
-        public IAsyncResult BeginAccept(int receiveSize, AsyncCallback callback, object state)
+        public IAsyncResult BeginAccept(int receiveSize, AsyncCallback? callback, object? state)
         {
             return BeginAccept(null, receiveSize, callback, state);
         }
 
         // This is the truly async version that uses AcceptEx.
-        public IAsyncResult BeginAccept(Socket? acceptSocket, int receiveSize, AsyncCallback callback, object state)
+        public IAsyncResult BeginAccept(Socket? acceptSocket, int receiveSize, AsyncCallback? callback, object? state)
         {
             if (NetEventSource.IsEnabled) NetEventSource.Enter(this);
             ThrowIfDisposed();
@@ -3865,6 +3865,11 @@ public bool DisconnectAsync(SocketAsyncEventArgs e)
             // Throw if socket disposed
             ThrowIfDisposed();
 
+            if (e == null)
+            {
+                throw new ArgumentNullException(nameof(e));
+            }
+
             // Prepare for and make the native call.
             e.StartOperationCommon(this, SocketAsyncOperation.Disconnect);
             SocketError socketError = SocketError.Success;
@@ -5023,7 +5028,7 @@ private void ValidateBlockingMode()
         partial void ValidateForMultiConnect(bool isMultiEndpoint);
 
         // Helper for SendFile implementations
-        private static FileStream? OpenFile(string name) => string.IsNullOrEmpty(name) ? null : File.OpenRead(name);
+        private static FileStream? OpenFile(string? name) => string.IsNullOrEmpty(name) ? null : File.OpenRead(name);
 
         private void UpdateReceiveSocketErrorForDisposed(ref SocketError socketError, int bytesTransferred)
         {

src/libraries/System.Net.Sockets/src/System/Net/Sockets/SocketAsyncEventArgs.cs

@@ -318,7 +318,7 @@ internal void CopyBufferFrom(SocketAsyncEventArgs source)
             }
         }
 
-        public void SetBuffer(byte[] buffer, int offset, int count)
+        public void SetBuffer(byte[]? buffer, int offset, int count)
         {
             StartConfiguring();
             try

src/libraries/System.Net.Sockets/src/System/Net/Sockets/SocketPal.Unix.cs

@@ -1098,7 +1098,7 @@ public static SocketError ReceiveFrom(SafeSocketHandle handle, byte[] buffer, in
             return completed ? errorCode : SocketError.WouldBlock;
         }
 
-        public static SocketError WindowsIoctl(SafeSocketHandle handle, int ioControlCode, byte[] optionInValue, byte[] optionOutValue, out int optionLength)
+        public static SocketError WindowsIoctl(SafeSocketHandle handle, int ioControlCode, byte[]? optionInValue, byte[]? optionOutValue, out int optionLength)
         {
             // Three codes are called out in the Winsock IOCTLs documentation as "The following Unix IOCTL codes (commands) are supported." They are
             // also the three codes available for use with ioctlsocket on Windows. Developers should be discouraged from using Socket.IOControl in
@@ -1316,7 +1316,7 @@ public static unsafe SocketError GetSockOpt(SafeSocketHandle handle, SocketOptio
             return err == Interop.Error.SUCCESS ? SocketError.Success : GetSocketErrorForErrorCode(err);
         }
 
-        public static unsafe SocketError GetSockOpt(SafeSocketHandle handle, SocketOptionLevel optionLevel, SocketOptionName optionName, byte[]? optionValue, ref int optionLength)
+        public static unsafe SocketError GetSockOpt(SafeSocketHandle handle, SocketOptionLevel optionLevel, SocketOptionName optionName, byte[] optionValue, ref int optionLength)
         {
             int optLen = optionLength;
 

src/libraries/System.Net.Sockets/src/System/Net/Sockets/SocketPal.Windows.cs

@@ -716,7 +716,7 @@ public static SocketError GetSockOpt(SafeSocketHandle handle, SocketOptionLevel
             return errorCode == SocketError.SocketError ? GetLastSocketError() : SocketError.Success;
         }
 
-        public static SocketError GetSockOpt(SafeSocketHandle handle, SocketOptionLevel optionLevel, SocketOptionName optionName, byte[]? optionValue, ref int optionLength)
+        public static SocketError GetSockOpt(SafeSocketHandle handle, SocketOptionLevel optionLevel, SocketOptionName optionName, byte[] optionValue, ref int optionLength)
         {
             if (optionLevel == SocketOptionLevel.Tcp &&
                 (optionName == SocketOptionName.TcpKeepAliveTime || optionName == SocketOptionName.TcpKeepAliveInterval) &&

src/libraries/System.Net.Sockets/src/System/Net/Sockets/TCPListener.cs

@@ -224,7 +224,7 @@ public TcpClient AcceptTcpClient()
             return returnValue;
         }
 
-        public IAsyncResult BeginAcceptSocket(AsyncCallback callback, object state)
+        public IAsyncResult BeginAcceptSocket(AsyncCallback? callback, object? state)
         {
             if (NetEventSource.IsEnabled) NetEventSource.Enter(this);
 
@@ -262,7 +262,7 @@ public Socket EndAcceptSocket(IAsyncResult asyncResult)
             return socket;
         }
 
-        public IAsyncResult BeginAcceptTcpClient(AsyncCallback callback, object state)
+        public IAsyncResult BeginAcceptTcpClient(AsyncCallback? callback, object? state)
         {
             if (NetEventSource.IsEnabled) NetEventSource.Enter(this);